Electromagnets



2, 1958 A. w. VINCENT 2,847,620

ELECTROMAGNETS Filed Jan. 25, 1954 INVEN TOR. FWD/FEW w. v//vc/v7 United States Patent ELECTROMAGNETS Andrew W. Vincent, Rochester, N. Y.

Application January 25, 1954, Serial No. 405,797

9 Claims. (Cl. 317-189) This invent-ion relates to electromagnets.

The main purpose of the present invention is the production of an electromagnet having a small movement of its armature in swinging through a very narrow gap in an efiicient magnetic circuit, together with a compact etficient linkage to cause the large forces developed at the armature to be translated into relatively large output motion.

A further purpose of the invention is the production of an electronragnet in which the movable armature thereof cooperates with a motion amplifying linkage in which the several moving parts thereof utilize rotating line bearings as distinguished from sliding bearings, whereby the electromagnet operates promptly and reliably through millions of operations.

The various features and advantages of the invention will appear from the detailed description and claims when taken with the drawings in which:

Fig. l is a top view of the present electromagnet;

Fig. 2 is a similar top View thereof with the link 30 omitted therefrom;

Figs. 3, 4 and 5 are respectively a side elevation, an end view and a bottom view of the present invention; and

Fig. 6 is a greatly enlarged fragmentary view taken on the section line 6-6 of Fig. 4 looking in the direction of the arrows.

In the drawings, the numeral 5 designates a horse-shoe core having the parallel legs 6 and 7, the core being made preferably of magnetically annealed Armco iron bar stock, rectangular in cross section. The leg 7 of the core is inserted through an energizing coil 8 of approximately the length of this leg, the coil being provided with terminals T. The legs 6 and 7 have their free ends or poles 9 and 10 ground to fiat surfaces, the planes of which are held in alinement by a stainless steel Wire 11 (Fig. 3) welded at each of its ends, to points on the front side of the legs near their free ends. The wire is made of stainless steel to prevent shunting the lines of force and serves to retain the coil 8 in proper position on the core while holding the legs 6 and '7 against spreading which would misaline the pole surfaces.

A flat rectangular block armature 12 also made of Armco iron magnetically annealed, is of such area that it covers the ends or poles 9 and 10 of the legs 6 and 7, and also bridges the space therebetween. This armature is swingingly mounted on a metal leaf hinge 13 welded to the lower surfaces (Fig. 3) of the leg 6 and the armature respectively. Thus the armature on attraction thereof, swings or rocks from its normal position with the extremely narrow gap G (Fig. 6), to the position in which its inner surface snugly contacts the flat ends or poles of the core.

As best shown in Fig. 5, the leaf spring 13 comprises a band portion 13 which bridges the crack between the leg 6 and the lower end of the armature 12 and extends the entire length of the crack. The band has integral tabs 13" projecting from its respective ends at one edge thereof for Welding to the outer surface of leg 6 near its free end while the band also has an integral tab 13" projecting from an intermediate portion of its other edge, for welding to the 2,847,620 Patented Aug. 12, 1958 bottom of the armature 12. It will be noted that the integral tabs 13" and 13" hold the related parts of leg 6 and armature 12 in proper alinement while the narrow band 13' bends in torsion permitting the armature to rock on the pole surface 9. It will also be noted that hinge 13 pivots the armature so that it is held for rocking or rotating motion and in the normal or rest position of the armature, the lower edge of its inner surface rests against the pole surface 9 with essentially a line contact or hearing A at the axis of rotation. Such a core-armature contact, will withstand the large forces developed by the magnet without substantial wear since the contact line broadens until it includes the entire end surface of the pole-piece as the armature closes the gap G. It will be understood that the force on the line contact in the rest position of the armature is substantially zero but this force increases progressively to a large value as the line contact broadens until it embraces the entire end area of pole face 9.

The armature carries an integral frame F conveniently made of sheet steel. This frame has a top portion bridging the upper end of the armature, with integral lateral supporting strips 15 welded at 16 to the sides of the armature. The frame comprises a substantially rigid upright cross strip 17 facing the end of the coil, the cross strip being provided with an upstanding lug 18 intermediate its ends. Each of the supporting strips 15 at its upper end has an apertured ear 19 connected by a triangular wing 20 to the upper edge of the cross strip 17. The apertures in ears 19 receive an adjusting screw 21, one of the apertures being tapped so that adjustment of the screw can vary the spacing between the ears 19 whereby a force is transmitted through the wings 20 to flex the cross strip 17 in order to move its intermediate portion with respect to pole 10. This flexing of cross strip adjusts the position of the lug 18 with respect to the airgap G.

Since the are of movement or throw of the armature has been sacrificed in order to have a narrow airgap G with a consequent large force at the armature, a mechanical linkage related to the armature, is provided. This linkage and its related parts translate the large force at the armature into a relatively large output motion.

The linkage includes a substantially rigid fulcrum blade 22 of stainless steel which is preferably coextensive with the width of the leg 7 and is Welded to the top surface thereof. This blade extends from the leg 7 through the space between the lower edge of cross strip 17 and the upper edge of the armature, to terminate except for a slotted extension 37 in a straight fulcrum edge 23 which is parallel to the principal surfaces of the armature. This edge provides a fulcrum bearing B for the lever 24. Lever 24 is generally U-shaped in outline (Fig. 4) to define two upstanding members 25 separated by a cutout portion 26. The lower part of the lever has an arm 27 integral therewith and extending transversely of the lever from one edge thereof to the other edge Where the free end 28 of the arm is offset toward hearing A of the armature for connection to a member (not shown) to be moved by the magnet. The upper ends of the lever members 25 project through alined slots in one end of a rigid link 30, the inner alined edges of these slots constituting a bearing C on which the upper end of the lever 24, rocks. The other end of link 30 is provided with a short slot 31, to be engaged by the lug 18 on the armature frame.

It will be noted that the edge of slot 31 nearest the coil 8, serves as a line bearing D, for the rocking movement of the link 3t with respect to lug 1d. The bearing D is relatively short so that the link 30 can move slightly in its own plane in relation to lug 18, in order to compensate for tolerance variations in the several parts and to permit the airgap G to close throughout its length. The mentioned movement of link 30 in its own plane, allows the bearings B and C to be effective throughout their respective lengths. Although the length of the hearing D is relatively short, it is able to carry its load since the link 30 during operation, rotates very little with respect to the lug 18 on the armature frame. rotation results from the fact that the bearings A, B and C are in line as indicated by the broken line in Fig. 6.

The upper ends of the lever members 25 are held snugly against the fulcrum bearing B as well as against the bearing C by the hooked ends 32 and 33 respectively on the retaining springs 34- and 35. These springs are preferably made integral from sheet metal and are se cured to opposite faces of the lever 24 to extend upward over the lever cutout 26.

It will be noted that the hooked end 32 of restraining spring 34 engages a rectangular slot 36 in the fulcrum blade extension 37 which projects into the cutout portion 26 of the lever (Figs. 2 and 6). One edge of slot 36 is alined with the end edge of the blade 22, in other words the mentioned edge of the slot lies in the line bearing B.

The hooked end 33 on retaining spring 35, engages a rectangular slot 33 in the link 30. The slot 38 has an edge which is contacted by the hook 33, this edge being in alinement with certain edges of the adjacent slots in link 30 so that the several mentioned edges are in the line bearing C.

In the operation of this electromagnet, when the coil 8 is energized, the armature 12 is attracted to swing about its line hearing A into contact with the pole faces 9 and thereby closing the extremely narrow air gap G. This attraction of the armature, develops a relatively large force thereat but a relatively small motion. In order to translate this force into a larger output motion, the frame F carried on the armature draws the link 30 toward the left (Fig. 6). The link 39 which is connected to the short arm of lever 24 through line bearing C swings this lever on its fulcrum or line bearing B, thereby developing a large output motion of the element 28 carried by the long arm of lever 24.

The magnetic circuit of the present electromagnet is preferably so designed that the reluctance of the gap G is substantially equal to the reluctance of the core 5, although the invention is not limited to that construction.

It will be understood that there can be modificaions and variations of this electromagnet within the scope of the appended claims, without departing from the spirit of the present invention.

What I claim is:

1. In an electromagnet, a core provided with flat aligned pole faces, an energizing coil on said core, an

armature hingedly mounted at one of its ends on one of said pole faces leaving its opposite end free to swing toward the other pole face to close the air gap therebetween whereby the armature engages said pole faces when the coil is energized, the reluctance of said air gap being substantially equal to the reluctance of said core, a support adjacent the free end of the armature provided with a line bearing, a lever mounted near its first end for rocking movement about said line bearing to extend in the direction of the hinged end of the armature, and a link connecting the free end of the armature tosaid first end of the lever.

2. In an electromagnet, a core provided with flat aligned pole faces, an energizing coil on said core, an armature hingedly mounted at one of its ends to rock on one of said pole faces as a line bearing and leaving its opposite end free to swing whereby the armature engages said pole faces when the coil is energized, a support adjacent the free end of the armature provided with a line bearing, a lever mounted near its first end for rocking movement about said line bearing to extend in the direction of the hinged end of the armature, and a link connecting the free end of the armature to said first end of the lever and providing a line bearing with said lever.

3. In an electromagnet, a core provided with flat This small aligned polefaces, an energizing coil on said core, an armature hingedly mounted at one of its ends to rock on one of said pole faces as a line bearing and leaving its opposite end free to swing whereby the armature engages said pole faces when the coil is energized, a support adjacent the free end of the armature provided with a line bearing, a lever mounted near its first end for rocking movement about said line bearing on the support to extend in the direction of the hinged end of the armature, and a link connecting the free end of the armature to said first end of the lever and providing a line bearing with said lever, said three line bearings being parallel to each other and being arranged in a straight row.

4. In an electromagnet, a core provided with fiat aligned pole faces, an energizing coil on said core, an armature hingedly mounted at one of its ends on one of said pole faces as a line bearing and leaving its opposite end free to swing toward the other pole face to close the air gap therebetween whereby the armature engages said pole faces when the coil is energized, a frame mounted on the free end of said armature, said frame being provided with an adjustable lug thereon, a support adjacent the free end of the armature provided with a line bearing, a lever mounted near its first end for rocking movement about said line bearing on the support to extend in the direction of the hinged end of the armature, and a link connecting said lug to said first end of the lever and providing a line'bearing with said lever and with said lug.

5. In an electromagnet, a core provided with flat aligned pole faces, an energizing coil on said core, an armature hingedly mounted at one of its ends on one of said pole faces as a line bearing and leaving its opposite end free to swing toward the other pole face to close the air gap therebetween whereby the armature engages said pole faces when the coil is energized, a frame mounted on the free end of said armature, said frame comprising a substantially rigid cross strip extending in a plane generally parallel to a pole face, said cross strip being provided with a lug intermediate its ends, and means for flexing said cross strip whereby said lug can be adjusted with respect to said last mentioned pole face.

6. In an electromagnet, a core provided with fiat aligned pole faces, an energizing coil on said core, an armature hingedly mounted to one of its ends on one of said pole faces as a line bearing and leaving its opposite end free to swing toward the other pole face to close the air gap therebetween whereby the armature engages said pole faces when the coil is energized, a frame carried on the armature comprising a substantially rigid cross strip extending in a plane generally parallel to one of said pole faces, a lug carried on an intermediate portion of said cross strip, a pair of ears on said frame connected by triangular pieces to the ends of said strip and means for changing the space between said ears whereby said strip can be adjustably flexed whereby said lug can be moved with respect to said pole face.

7. An electromagnet comprising a U-shaped core of magnetic material having a first leg and a second leg arranged substantially parallel to each other, both legs terminating in flat pole faces lying substantially in a common plane approximately perpendicular to the lengths of said legs, an electromagnetic coil encircling said first leg, an armature, a flexible hinge connecting said armature to said second leg substantially at an edge of said second leg remote from said first leg, said armature extending from said hinge across the pole faces of both legs in normal-1y slightly spaced relation to the pole face of said first leg and in position to lie substantially flat against the pole face of said first leg when magnetically attracted thereto by fiow of electric current through said coil, a fulcrum member mounted on said first leg and projecting forwardly in the direction of said first leg to a position forwardly of said armature, an extension structure mounted on and movable bodily with said armature and extending laterally beyond said fulcrum member in a direction away from said second leg, a lever fulcrumed on said fulcrum member intermediate its ends and having a relatively short arm extending from said fulcrum member in a general direction away from said second leg and a relatively long arm extending from said fulcrum member in a general direction toward said second leg and projecting beyond the hinged end of said armature, and a tension link operatively connecting said short arm of said lever to said extension structure on said armature, so that when said armature is attracted and moves toward said pole face of said first leg, said link will pull said short arm of said lever in a general direction toward said pole face of said first leg and will swing the opposite end of said long arm of said lever in a general direction away from the pole face of said second leg through a substantially greater range of travel than that of said armature, whereby a part to be operated through a relatively great range of travel may be connected to and moved by said long arm of said lever while keeping the range of travel of said armature relatively small and keeping the magnet assembly relatively compact.

8. A construction as defined in claim 7, in which the hinge connection of said armature to said second leg, the point of connection of said link to said lever, and the point at which said lever is fulcrumed on said fulcrum member all lie substantially in a straight line.

9. A construction as defined in claim 7, in which said extension member includes a strut member capable of being flexed, said tension link being connected to said strut member, and an adjusting screw for flexing said strut member to vary the position of said link and said lever for a given position of said armature.

References Cited in the file of this patent UNITED STATES PATENTS 1,331,882 Stone Feb. 24, 1920 1,396,845 James Nov. 15, 1921 1,981,259 Wertz Nov. 20, 1934 2,180,288 Beach Nov. 14, 1939 2,291,923 Schmidt Aug. 4, 1942 2,618,713 Blinn Nov. 18, 1952 

